Antihalation backing for photographic silver halide recording elements



United States Patent 3 511,660 ANTIHALATION BACkING FOR PHOTOGRAPHIC SILVER HALIDE RECORDING ELEMENTS Guy William Willis Stevens, Harrow, England, and Claude Masson, Vincennes, France, assignor to Eastman Kot'lak Company, Rochester, N.Y., a corporation of New ersey No Drawing. Filed Oct. 18, 1966, Ser. No. 587,398 Claims. priority, application Great Britain, Oct. 19, 1965, 44,276/65; France, Dec. 1, 1965, 40,414 Int. Cl. G03c 1/84 U.S. Cl.96---84 8 Claims ABSTRACT ;.OF THE DISCLOSURE A photographic element comprises a support having on one side a photosensitive layer such as a silver halide emulsion and on the other side an antihalation layer compising; carbon black in a binder such as cellulose acetate phthalate and having colloidal silver in the antihalation layer. The colloidal silver inhibits fading, etc., caused by carbon black contacting the silver halide in film rolls and the like.

The present invention relates to sensitive photographic materials,1-especially sensitive silver halide coated films having backing layers.

When sensitive photographic films which have layers coatedon the rear side of the support are packed so that therear sideof one piece of film presses in contact with the front sensitive side of another piece, problems sometimes arise caused by undesirable effects produced on storing the films so packed, where substances present in the backing layer adversely affect the sensitive layers. This kind of trouble can sometimes be very serious in the case of rolls of films because in almost every convolutionyof the roll, some part of the rear surface is pressing against the front surface of the next convolution.

Of the. manysubstances which have been suggested for making light absorbing and antihalation layers, carbon black is especially suitable. However, we have found that most, if not all, available commercial carbon black, when incorporated in the backing layer of sensitive films, especially films bearing on their front surface a highly sensitive gelatino-silver halide emulsion layer, produce undesirable: effects of the kind referred to, especially when the film is stored for long periods in rolls in climates of rather high humidity. In the case of this carbon black the effect, may be particularly serious when the silver halide layer has been exposed imagewise and therefore contains a latent image. On storage of such exposed film in high humidity conditions, the carbon black produces an undesirable fading of the latent image and of course this fading is usually not uniform but varies area by area according to the tightness of the contact in the convolutions of the roll.

Since the reason why some carbon black produces this undesirable effect even when in a binder, such as cellulose acetate phthalate is obscure, it has been extremely difiicult to overcome. We have now found however, that the effect can be eliminated or reduced to such a low degree as; to be insignificant, by incorporating colloidal silver in the layer containing the carbon black or by coating over the carbon black layer a separate layer contaming the colloidal silver.

For simplicity of manufacture, it is preferred that the colloidal. silver be added to the coating solution used for coating the carbon black layer. While small propor- 3,511,660 Patented May 12, 1970 ice tious of colloidal silver to carbon can be usually added without difliculty, there is a tendency in the case of many vehicles, especially the organic solvent soluble vehicles such as cellulose acetate phthalate, for the carbon and sllver to fiocculate each other, especially in cases Where the carbon black is itself in a state of incipient flocculatlon. In order therefore to incorporate larger and more useful quantities of colloidal silver without flocculation of either the silver or the carbon occurring, we have found that the following procedure should be adopted.

(A) Disperse the carbon black in a solution of the binder, such as cellulose acetate phthalate, using as solvent a mixture of water with a water-miscible organic liquid which is itself a solvent for the binder.

(B) Make a dispersion of colloidal silver in a mixture of water with a water-miscible organic liquid which is itself a solvent for the binder used for (A).

These two dispersions (A) and (B) are then simply mixed together with stirring.

This method permits the incorporation of colloidal silver to the dispersion of carbon black in the solvent medium containing the cellulosic binder, used for coating the antihalation backing layer.

It is also possible to disperse beforehand the colloidal silver in the cellulose binder in a solvent medium and to add this preparation to the carbon black dispersion.

The quantities to be added are such that the silver to carbon ratio by weight may vary from 1 to to l to 2 but we prefer to use quantities between 1 to 30 and I to 4 of silver having the particle size described herein. The important property of the silver is its particle size so that using smaller particle sizes allows the weight to be reduced and vice versa.

For incorporating the colloidal silver by this method, the carbon black is first completely dispersed in a solvent medium of the cellulose binder (A), then diluted with a mixture which is equally a solvent, of the cellulose binder, but containing a dispersion of colloidal silver in an aqueous medium (B).

The following examples illustrate the invention.

EXAMPLE 1 Twenty-five grams of polyvinyl phthalate (19% phthalyl) are dispersed in the following mixture:

Ml. Ethylene glycolmonomethyl ether 140 Ethanol 90 Water 30 To the dispersion so made there is then added the following dispersion of colloidal silver:

Ethylene glycolrnonomethyl ether Ethanol 376 Acetone 123 12.5% by weight Codex-type colloidal silver in water 120 Forty-two grams of a solid dispersion comprising /3 of carbon black in of cellulose acetate hexahydro phthalate are dissolved in:

M1. Ethylene glycolmonomethyl ether 150 Ethanol 300 Acetone 63 Water 75 The carbon black particles had a diameter of about 30 millimicrons. After dissolution, the following mixture is added with stirring:

4 After dissolution, there was added with agitation the following mixture:

Ethylene glycolmonomethyl ether Th coat g pr u r m this backing silver/ Ethanol 166 carbon ratio 1:9 and a control coated with no silver ad- Acetone 6O 15 itien were tested by the procedure described in Exam- Water 75 ple 1.

Density values Control backing Backing with silver Control Contact Control Contact Test conditions area area Difference area area Difference 70% EH. 8 days at 105 F 1. 10 1.24 +0. 14 1. l. 08 +0.03

The resulting mixed dispersion, which has a 1:12 silver/ carbon ratio and is very stable, is coated on the back of film base to give a layer containingl5-20 mg. of silver per square meter. The resistivity of the layer is not higher than 0.20X 9/cm./ cm.

This layer and a control without the silver addition were tested by contacting with a reversal color film exposed to white light to give a neutral density around 1 after commercial processing. Before contacting, both emulsioncoated and backing-coated films were conditioned to a Again the backing with silver produced a markedly decreased density and color change.

EXAMPLE 3 A carbon-black-silver layer was made up exactly as in Example 2, except that cellulose acetate hexahydro phthalate was substituted for the cellulose acetate phthalate.

The coatings produced from this backing and a control coated with no silver addition were tested by the procedure described in Example 1.

Density values Control backing Backing with silver Control Contact Control Contact Test conditions area area Difierence area area Difference RE. 3 days 0 9 1 0 2 0. 07 0.92 9 80% R.H. 3weeks 0 6 +0 04 at 70 F l. 28 1. 38 +0. 10 1. 22 1. 26 +0. 04

EXAMPLE 2 Forty-two grams of a solid dispersion comprising /3 of carbon black in /3 of cellulose acetate phthalate were dispersed in:

M1. Ethylene glycolmonomethyl ether 150 Ethanol 300 Acetone 63 Water In both testing conditions, the backing with silver prouced significantly smaller density and color changes.

EXAMPLE 4 Thirty grams of Peerless carbon black sold by Colum- 60 bian Carbon Company are added to 1.5 grams of Codex colloidal silver dissolved in 250 ml. of a mixture of 1,000 ml. ethylene glycolmonomethyl ether and 100 ml. of water, and the mixture is stirred for 2-3 days, then it is filtered, washed with distilled water and dried at C.

Fourteen grams of the dry mixture were then dispersed in 28 grams of cellulose acetate hexahydro phthalate to which was added diethyleneglycol monomethyl ether (methyl Carbitol) (11 grams).

Forty-two grams of the resulting dry mixture was then added to:

Ml. Ethylene glycolmonomethyl ether 140 Ethanol Water IIIIIIIIIIIIIIIIII:11:11:: 30

To the dispersion there was then added:

In both tests, the clear overcoated control B produced larger color and density changes than the plain Ethylene glycohnonomethyl ether control A. The silver-containing overcoat prevented all color change. 22:23: I Will be understood that modifications and variations Water. 120 y e made Wi hin the scope of the invention as desc bed above and as defined in the following claims.

The resulting product was then coated to give a layer we clalmi bearing 5-7 mg. of silver per square meter and having a In a p q p COmPFISIIIg a 1 1 i ti it f b ozox109n/ mg on one side a photosensitive layer and on the other The coatings produced from this backing and from a slde f antlhalatlofl baclflng layer Whlch hfjls P f control, with no silver addition were tested by the procetherein carbol} black, an lmPl'ovement Wherfim fi 311th dure describedin Example 1. n halation backing layer contains colloidal silver therein.

Density values Control backing Backing with silver Control Contact Control Contact Test conditions area area Difierence area area Difl'erenco 70 RH. 3d

Z? 105 0. 95 1. 02 +0. 07 0. 92 0.96 +0.04 80% RH. 3 weeks at 70 F 1. 2a 1.38 +0.10 1. 21 1. 23 +0. 02

EXAMPLE 5 2. A photographic element of claim 1 in which the sup- Twelve ml. of a Carey Lea silver sol containing 1.6 percent by weight colloidal silver in 3 percent by weight gelatin at 40 C. was mixed with ml. of water at 40 C.I,This Inixturewas then poured slowly with stirring into 41ml. of a solution containing:

Percent by volume Methyl Cellosolve 19.4 Acetone Ethyl. alcohol 60.6

Both the silver and gelatin remained satisfactorily dispersed. The resultant mixture was then poured with rapid stirring in 26 ml. of a solution produced from:

Cellulose acetate phthalate, grams 30 Methyl Cellosolve, ml. 140 Ethylalcohol, ml. 90 Water (distilled), ml. 30

The mixture was then coated over a carbon/black coating,.such as the control of Example 1. This composite coating was labeled C. As controls were used, the plain carbon backing (A) and the carbon backing supercoated with a similar cellulose acetate phthalate solution without any silver added (B).

The three coatings were tested as in Example 1, with the following results.

*Thedenslty loss shown by this test was caused solely by physica pinholes resulting from backing stripping, and not'from chemical photo graphic action of the backing.

port is film base.

3. A photographic element of claim 1 wherein the ratio of said colloidal silver to said carbon black is in the range from about 1 to 100 to about 1 to 2 parts, by weight.

4. A photographic element of claim 3 wherein said ratio of colloidal silver to carbon black is in the range from about 1 to to about 1 to 4 parts, by weight.

5. An element of claim 1 in which said carbon black is dispersed in cellulose acetate phthalate.

6. An element of claim 1 in which said carbon black is dispersed in cellulose acetate hexahydrophthalate.

7. An element of claim 1 in which said carbon black is dispersed in polyvinyl phthalate.

8. A photographic element of claim 1 in which said 40 photosensitive layer is a silver halide emulsion.

References Cited UNITED STATES PATENTS 2,694,622 11/1954 I Iunter 96-84 XR 3,163,533 12/1964 Derr 96-22 XR 3,247,127 4/1966 Bailey 96-84 XR 2,346,078 4/1944 Nadeau et al. 96-84 2,448,507 9/1948 Alles 96-84 2,462,534 2/ 1949 Murray 9 6-84 2,968,582 l/ 1961 Salminen et al. 96-87 3,152,252 10/1964 Wainwright et al. 96-84 3,222,178 12/1965 Nadeau et a1 96-87 XR 3,234,023 2/1966 De Ramaix et al 96-84 3,269,252 8/ 1966 De Keyser et al 9 6-84 3,340,062 9/ 1967 Hunter et al. 96-84 FOREIGN PATENTS 583,508 12/ 1946 Great Britain.

RONALD H. SMITH, Primary Examiner US. Cl. X.R. 

